Module documentation for 0.1.0.8

hdevtools

About

hdevtools is a backend for text editor plugins, to allow for things such as
syntax and type checking of Haskell code, and retrieving type information, all
directly from within your text editor.

The advantage that hdevtools has over competitors, is that it runs silently
in a persistent background process, and therefore is able to keeps all of your
Haskell modules and dependent libraries loaded in memory. This way, when you
change only a single source file, only it needs to be reloaded and rechecked,
instead of having to reload everything.

This makes hdevtools very fast for checking syntax and type errors (runs just
as fast as the :reload command in GHCi).

In fact, syntax and type checking is so fast, that you can safely enable auto
checking on every save. Even for huge projects, checking is nearly instant.

Once you start using hdevtools and you get used to having your errors shown
to you instantly (without having to switch back and forth between GHCi and your
editor), and shown directly on your code, in your editor (without having to
wait forever for GHC to run) you will wonder how you ever lived without it.

In addition to checking Haskell source code for errors, hdevtools has tools
for getting info about identifiers, and getting type information for snippets
of code.

Text Editor Integration

hdevtools is designed to be integrated into text editors. The list of current
editor plugins that supply this integration is below.

But before you do anything, you must first install hdevtools itself. The
easiest way is from Stackage using stack:

Syntastic is a popular syntax checking plugin for Vim, and is the
recommended Vim integration of hdevtools syntax and type checking. Recent
versions of Syntastic(since Sep. 2012) have builtin support for hdevtools.

In addition to Syntastic, it is recommended that you also use
vim-hdevtools for additional functionality.

vim-hdevtools offers integration with the rest of the hdevtools tools,
including retrieving info about the identifier under the cursor, and getting
the type of the code under the cursor. Refer to its documentation for more
details.

Manual Editor Integration for any Editor

Most editors allow you to run a make command, and will then parse the output
for errors and show line numbers, allowing you to jump between errors.

The hdevtools check command is suitable for such usage.

For example, in Vim something like this will work:

:let &makeprg='hdevtools check %'

(Vim will replace the % character with the name of the current file). Then
you can run

:make

And Vim will invoke hdevtools to check the current file for errors, and then
show a list of them and allow jumping to them.

See the "Command Line Usage" section below for more information.

Command Line Usage

Note: When using one of the above editor plugins, you don't really need to know
this.

Available Commands and Help

For the list of commands available, run:

$ hdevtools --help

To get help for a specific command, run:

$ hdevtools [COMMAND] --help

For example:

$ hdevtools check --help

The hdevtools background process

The first time hdevtools runs a command, it will spawn a background process
that will remain running forever. You can check the status of this background
process by running:

$ hdevtools --status

You can shutdown the background process by running:

$ hdevtools --stop-server

Communication with the background process is done through a unix socket file.
The default name is .hdevtools.sock, in the current directory. This allows
you to use hdevtools with multiple projects simultaneously, without the
background processes getting in the way of each other.

You can use a different socket file name with the --socket option, which
should be used for each invocation of hdevtools. Remember that when telling
hdevtools to check a Haskell file, paths are relative to the path of the
background process, not your current directory. This can cause problems, and
therefore it is recommended that you leave the socket file as the default, and
always run hdevtools from the same directory.

You can specify the path to a target file with the --path option. This is
useful for integration with IDEs that submit a copy of the original source
file (in a temporary directory) to hdevtools making it impossible to extract
the .cabal information for the file's project. In such cases, you can run as:

$ hdevtools check -p /path/to/file.hs /tmp/file.hs

and hdevtools will use the given path to obtain the .cabal information.

Specifying GHC Options

For most non-trivial projects, you will need to tell hdevtools about
additional GHC options that your project requires.

Credits

Changes

Changelog

0.1.6.0 - 2017-08-21

Added handling of source errors: GHC SourceError and other exceptions are
now correctly sent to the frontend process. This enables hdevtools to
correctly report haskell syntax errors and improves visibility of exceptions
leading the backend process to die.

.hdevtoolsrc file for project-specific configuration.

Use of stack can be turned off with --nostack.

0.1.5.0 - 2016-12-23

(Re-)added template haskell support when required. Can be turned off using --noth.

Fixed system installed GHC libdir paths using stack.

0.1.4.1 - 2016-09-04

Do not try to execute stack commands if not available.

0.1.4.0 - 2016-08-08

Determine GHC libdir and binaries using stack.

0.1.3.2 - 2016-06-09

Added GHC 8.0.x support

0.1.3.1 - 2016-05-13

Added support for new Cabal versions

Do not generate code, fixing inline-c modules typechecking

0.1.3.0 - 2016-02-29

Improved performance in stack projects: The stack configuration is
updated only when the passed path implies a different stack.yaml.
Performance improved substantially from roughly ~1s to ~0.3s.

0.1.2.2 - 2016-01-11

Added type checking support for tests and benchmarks in stack projects.